Fluid injection device

ABSTRACT

A fluid injection device includes a fluid supply unit that accommodates and supplies fluid, a fluid injection unit that injects fluid supplied from the fluid supply unit, and a driving waveform generating device which is equipped with at least one adjusting device, a one-input multiple-control parameter changing unit that simultaneously changes plural control parameters for determining a fluid injection condition of the fluid injection unit on the basis of a signal from the at least one adjusting device, and a driving waveform generator that generates and outputs a driving waveform of the fluid injection unit on the basis of the control parameters set by the one-input multiple-control parameter changing unit.

This application is a Continuation of U.S. patent application Ser. No.14/720,204 filed May 22, 2015, which is a Continuation of U.S. patentapplication Ser. No. 14/094,076 filed Dec. 2, 2013, which is aContinuation of U.S. patent application Ser. No. 13/846,557 filed onMar. 18, 2013, which is a Continuation of U.S. patent application Ser.No. 12/180,085 filed Jul. 25, 2008, which claims priority to JapanesePatent Application No. 2007-208961 filed on Aug. 10, 2007, the entirecontents of the above-referenced applications are herein incorporated byreference in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to a fluid injection device in which thecharacteristic of fluid to be injected can be easily set to a desiredstate in accordance with various situations.

2. Related Art

With respect to a surgery based on injected fluid, the substance of aninternal organ can be incised while preserving vasculature such as bloodvessels, and also incidental damage applied to living tissues other thanthe incised site is minor. Therefore, the load imposed on a patient issmall. Furthermore, bleeding is little, so that bleeding does notdisturb the field of vision of an operational field and thus a rapidoperation (surgery) can be performed. Therefore, this operation isfrequently clinically applied particularly to hepatic resection, etc. inwhich bleeding from small blood vessels gives a lot of trouble (forexample, JP-A-63-99853).

In the technique as disclosed in the above publication, a pump as apressurizing source of liquid (fluid) is provided at the outside, andhigh-pressure fluid is led through a flexible tube to a treatment site.Therefore, even when pressure pulsation is generated by the pressurizingsource, injection of the fluid causes continuum flow because the tubehas elasticity. When the injection of fluid is pulsated flow, theincision (exsection) performance is enhanced by impact of bow wave.However, when the injection of fluid is continuum flow, the incisionperformance of living tissues is insufficient, and also the flow amountto be injected is large. Therefore, droplets of living tissues, etc.from the incision (exsection) site easily fly and these droplets mayintroduce an infection to an operator.

As an improvement proposal of the fluid injection device as describedabove is known a method of generating fluid jet by which means formaking fluid flow is provided in a fluid chamber and vapor bubbles offluid is intermittently generated by heating means in the fluid chamberso that the internal pressure in the fluid chamber is intermittentlyincreased and pulsated fluid is injected at high speed (For example,JP-T-2003-500098).

Furthermore, a fluid injection device disclosed in JP-A-2005-152127which has been filed by the inventors of this application can injectpulsated fluid at high speed and high repetitive frequency, and thecontrol thereof is easy. Furthermore, the injection of the pulsatedfluid enhances the incision performance of tissues in the operation,etc., and also makes it possible to reduce the fluid amount, so that thefluid is little trapped in the operational field. Accordingly, thismethod has an effect of enhancing visibility and preventing scatteringof the tissues.

Only the generated pressure of the pump as the pressurizing source canbe set as a control parameter in JP-A-63-99853, however, various controlparameters can be set in the methods of disclosed in JP-T-2003-500098and JP-A-2005-152127. In JP-A-2005-152127, the wave height value ofpulsation, the frequency of pulsation, the pulsation number constitutinga fluid stream (group), the interval between fluid streams (groups),etc. can be set as the control parameters. By setting these valuesproperly, it is possible to properly exsect soft tissues of a livingbody whose hardness and structure vary every place.

For example, by increasing the wave height of pulsation, a harder tissuecan be exsected. However, in the case of the same tissue, incision ofthe tissue concerned progresses more deeply (i.e., a deeper tissue canbe also incised) by injecting the fluid for the same time. At this time,when a surgeon wants to make the exsection progress depth equal to thatbefore the adjustment, the adjustment can be performed by reducing thepulsation number constituting the fluid stream or increasing the timeinterval between the fluid streams to reduce the injected fluid amount.

Furthermore, when an fluid infusion bag or the like is used to supplyfluid to a fluid injection portion by using force of gravitation, theamount of fluid to be supplied is limited by the fluid resistance of afluid channel. At this time, if the control parameters are set so thatthe injection amount of fluid exceeds the limit of the supplied fluidamount, the injection state of the fluid is unstable, and the exsectionperformance may be reduced.

However, it is very difficult that these plural control parameters whichare mutually correlated with one another are properly adjusted by ansurgeon or an operator under the supervision of the surgeon during atime-limited operation. Furthermore, in a fluid injection device inwhich the supplied fluid amount is limited by the structure thereof,even when a surgeon wants to incise a tissue more deeply and thusincrease the pulsation number constituting the fluid stream, there is acase where no desired characteristic is obtained or the operation isunstable because the supplied fluid amount is limited.

SUMMARY

An advantage of the present invention is to solve at least a part of theforegoing problem, and can be implemented as the following embodiment orapplication example.

A fluid injection device according to an aspect of the present inventionincludes: a fluid supply unit that accommodates and supplies fluid; afluid injection unit that injects fluid supplied from the fluid supplyunit; and a driving waveform generating device including at least oneadjusting device, a one-input multiple-control parameter changing unitthat simultaneously changes plural control parameters for determining afluid injection condition of the fluid injection unit on the basis of asignal from the at least one adjusting device and a driving waveformgenerator that generates and outputs a driving waveform of the fluidinjection unit on the basis of the control parameters set by theone-input multiple-control parameter changing unit.

Here, the fluid injection condition means a variation state of theinjection speed of a fluid stream injected from a fluid injectionopening portion, and the adjusting device is an adjusting dial forselecting the hardness of a tissue as an exsection target.

According to the aspect of the present invention, an injection conditionof a fluid stream (group) which a surgeon desires can be rapidlyobtained. Therefore, the surgery time can be shortened, and the fatigueof the surgeon can be reduced. Furthermore, an erroneous operation ofthe surgeon or an operator under the supervision of the surgeon can bereduced, and a safe operation can be performed. Still furthermore, evenwhen the amount of supplied fluid is limited, unstable settings can beprevented from being set due to deficiency of the supplied fluid amount,so that a stable operation of the fluid injection device can beimplemented.

In the fluid injection device according to the aspect, it is preferablethat the driving waveform is constructed by a pulsating portion and aresting portion.

For example, when the driving waveform is constructed by a pulsatingportion including a waveform of an integer number of sequential sinewaves starting from −π/2 in phase and a resting portion at which nowaveform is output, the control parameters may be plural effective itemsselected from the amplitude of the sine waves, the frequency of the sinewaves, the number of the sequential sine waves and the length of theresting time. In this case, the injection of the fluid stream ispulsated by the waveform of the sequential sine waves, the incisionperformance of a tissue is enhanced, and also the flow amount can becontrolled by the resting time.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that the one-input multiple-controlparameter changing unit is equipped with an optimum driving controlparameter calculating device or an optimum control parameter settingtable.

The operation of the one-input multiple-control parameter changing unitin the fluid injection device according to the aspect is determined onthe basis of experiment results obtained by actually incising a modeltissue or the like. Accordingly, these results are described in theoptimum control parameter setting table along the experiment resultsrather than function approximation of the results, and the optimumcontrol parameter setting table is referred to as occasion demands,whereby the optimum driving waveform can be simply constructed.

Furthermore, on the basis of the signal selected and input by theadjusting device, the proper control parameters can be calculated by theoptimum driving control parameter calculating device to generate andoutput the optimum driving waveform.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that a plurality of optimum controlparameter setting tables are provided, and the driving waveformgenerating device is further equipped with an adjusting device thatselects one of the plural optimum control parameter setting tables.

The plural optimum control parameter setting tables are set inaccordance with a surgery site as a surgery target. In such a case, theoptimum control parameter setting table is selected on the basis of thesurgery site as the surgery target and the initial setting based on thehardness of the surgery site, and fluid is injected on the basis of thedriving waveform based on the selected optimum control parameter settingtable, whereby the fluid injection device can be properly adjusted undervarious conditions.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that the optimum control parameter settingtable is a time-series driving waveform indicating value within a fixedtime range.

The pulsating portion of the driving waveform is not limited to the sinewave described above. Accordingly, by providing the driving waveformincluding the pulsating portion and the resting portion on the basis ofthe driving waveform indicating value, a more proper fluid injectioncondition can be set in accordance with the hardness of the surgery siteor the exsection depth.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that the driving waveform generating deviceis further equipped with an adjusting device that sets the optimum gainof the generated driving waveform.

With this construction, only the gain of the driving waveform (that is,corresponding to the amplification factor of the voltage of the outputpulsating portion) can be changed by using the adjusting device beforeor during the surgery. Accordingly, only the gain can be adjusted inaccordance with the hardness of the surgery site or the exsection depthof the surgery site with changing neither the frequency nor the numberof sequential driving waves, and thus the surgeon can perform his/herdesired surgery.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that the fluid injection unit has anoperation environment detecting element therein, and the drivingwaveform generating device is equipped with a gain adjusting circuitthat sets the optimum gain of the driving waveform on the basis of adetection signal from the operation environment detecting element.

Here, the operation environment detecting element is typified by apressure sensor for fluid supplied to the fluid injection device, forexample.

In the above construction, the pressure of the fluid supplied to thefluid injection unit is detected by the pressure sensor, and thepressure detection value is taken into the gain adjusting circuit toadjust the gain of the driving waveform. Accordingly, the surgeon is notrequired to perform the adjusting operation and only the gain can beadjusted in accordance with the hardness and surgery depth of thesurgery site without affecting the frequency and the number of thesequential driving waves.

In the fluid injection device according to the aspect of the presentinvention, it is preferable that the driving waveform generating deviceis equipped with a pressure generator that supplies fluid to the fluidinjection unit under an indicated pressure.

With the above construction, even when the surgeon wishes to set such acondition that it is preferable to increase the amount of fluid to beinjected, the fluid is supplied under proper pressure of the pressuregenerator, so that the fluid stream can be stably injected.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram showing the schematic construction of a fluidinjection device according to a first embodiment.

FIG. 2 is a block diagram showing the inside of a driving waveformgenerating device according to the first embodiment.

FIG. 3 is a longitudinally sectional view of a fluid injection unitaccording to the first embodiment.

FIG. 4 is a graph showing an example of a driving voltage waveform ofthe fluid injection unit according to the first embodiment.

FIG. 5 is a block diagram showing the internal construction of a drivingwaveform generating device according to a second embodiment.

FIG. 6 shows a driving waveform formed by an optimum driving controlparameter table under low supply pressure according to a thirdembodiment.

FIG. 7 shows a driving waveform formed by the optimum driving controlparameter table under high supply pressure according to the thirdembodiment.

FIG. 8 is a longitudinally sectional view of a fluid injection unitaccording to a fourth embodiment.

FIG. 9 is a diagram showing the schematic construction of a fluidinjection device according to the fourth embodiment.

FIG. 10 is a block diagram showing the internal construction of a supplypressure control device according to the fourth embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments according to the present invention will bedescribed with reference to the accompanying drawings.

FIGS. 1 to 4 show a fluid injection unit of a fluid injection deviceaccording to a first embodiment, FIG. 5 shows a second embodiment, FIGS.6 and 7 show a third embodiment, and FIGS. 8 and 9 show a fourthembodiment. In the drawings referred to in the following description,the horizontal-vertical scales of members and portions are differentfrom the actual scales for convenience of illustration. Furthermore, thefluid injection device according to an embodiment of the presentinvention can be applied to various fields such as drawing using ink orthe like, cleaning of minute objects and structures, surgical scalpelblade, etc. In the embodiments described below, the invention will bedescribed by exemplifying a fluid injection device suitably used toincise or cut out a living body tissue, or a fluid injection devicesuitably combined with a catheter which is inserted in a blood vessel toremove blood clots or the like. Accordingly, fluid used in theseembodiments is water, normal saline solution or the like.

First Embodiment

FIG. 1 is a diagram showing the schematic construction of a fluidinjection device according to a first embodiment. In FIG. 1, the fluidinjection device 1 includes, as a basic construction, a fluid infusionbag 411 serving as a fluid supply unit that accommodates fluid thereinand supplies the fluid by the action of gravitational force, a fluidinjection unit 301 that varies fluid supplied by the gravitational forceto pulsation, and a driving waveform generating device 402.

The fluid infusion bag 411 and the fluid injection unit 301 areconnected to each other through a flexible connection tube 201. Thedriving waveform generating device 402 and the fluid injection unit 301are partially electrically connected to each other by a connection cable412 disposed along the connection tube 201. The driving waveformgenerating device 402 is equipped with an exsection hardness adjustingdial 423 as a kind of adjusting device and a driving controller 821 (seeFIG. 2).

FIG. 2 is a block diagram showing the internal construction of thedriving waveform generating device according to this embodiment. Anexsection hardness indicating value V3 indicated by the exsectionhardness adjusting dial 423 is input to the driving controller 821.Furthermore, an optimum driving control parameter calculating device asa one-input multiple-control parameter changing unit is provided in thedriving controller 821. Control parameters optimal to the exsectionhardness indicating value V3 are calculated and a fluid injection unitdriving voltage P2 corresponding to a target surgery site is output tothe fluid injection unit 301 by a driving waveform generator 822. Thisoperation will be described in more detail. The one-inputmultiple-control parameter changing unit means a device that cansimultaneously change at least two or more control parameters by oneinput.

FIG. 3 is a longitudinally sectional view of the fluid injection unit.In FIG. 3, a fluid chamber 332 to which fluid is supplied from theconnection tube 201 through an inlet pipe 121 is equipped with an inletvalve 314 at the entrance thereof and an outlet valve 313 at the exitthereof. The volume of the fluid chamber 332 varies by sagging of adiaphragm 303. The fluid injection unit driving voltage P2 is applied toa piezoelectric element 302, whereby the piezoelectric element 302expands and contracts and thus the diaphragm 303 sags. One end of thepiezoelectric element 302 is fixed to the bottom portion of a lid member305, and the peripheral edge of the lid member 305 is fixed to theperipheral edge portion of the diaphragm 303. Accordingly, the diaphragm303 sags by the expansion and contraction of the piezoelectric element302.

When the piezoelectric element 302 contracts, the volume of the fluidchamber 332 increases, so that the outlet valve 313 is closed and theinlet valve 314 is opened. As a result, the fluid supplied from theconnection tube 201 is sucked into the fluid chamber 332. When thepiezoelectric element 302 expands, the volume of the fluid chamber 332is reduced, so that the inlet valve 314 is closed and the outlet valve313 is opened. As a result, fluid is discharged from the fluid chamber332 to a connection fluid channel pipe 322.

The fluid discharged to the connection fluid channel pipe 322 makes ahigh-pressure portion under high pressure at the base portion of theconnection fluid channel pipe 322. This high-pressure portion moves atthe velocity of sound, and a fluid stream 901 under pulsation state isinjected from a fluid injection opening portion 334 formed at a tipmember 323. In order to minimize the attenuation of the pressure in theconnection fluid channel pipe 322, it is necessary to minimize thedeformation of the pipe line and the compression amount of fluid bypressure. Accordingly, the connection fluid channel pipe 322 is formedof a material having sufficient rigidity, and also the internal volumethereof is set to a requisite minimum value.

According to the above construction, the volume of the fluid chamber 332can be freely increased/reduced by expanding/contracting thepiezoelectric element 302. Therefore, various control parameters can beoptimally controlled, and also the control frequency can be set to 10KHz or more. Accordingly, even when the pulsation itself or the intervalbetween pulses is long, the surgeon can perform continuous exsectionwith the same feeling as a continuous stream. Furthermore, there is norise in the temperature of the injected fluid, and thus the operation(i.e., surgery) can be performed with safety.

Next, the one-input multi-control parameter change by the optimumdriving control parameter calculating device will be described withreference to FIG. 4 showing an example of the driving waveform. Thefluid injection unit driving voltage P2 in the example of FIG. 4 has apulsating portion including a waveform of an integer number ofsequential sine waves starting from −π/2 in phase and a resting portion(represented by a resting time I). The waveform of the pulsating portionis represented by the amplitude A, the period T and the number n ofsequential sine waves. The waveform of the pulsating portion is a burstwave, and it can be simply generated by indicating the above controlparameters through the driving wave generator 822.

With respect to the exsection of a tissue by injecting pulsating fluid,as the intensity of the pulsation is large, a large tissue can beexsected. This can be implemented by increasing the amplitude A of thefluid injection unit driving voltage in FIG. 4. In this case, however,the amount of fluid to be injected per unit time is increased. As aresult, the exsection depth per unit time is also increased. When thesurgeon does not want increase of the exsection depth per unit time, itis necessary to reduce the number n of sequential sine waves to a propervalue or increase the resting time I simultaneously with increase of theamplitude A.

In this embodiment, when the exsection hardness adjusting dial 423 isoperated, the amplitude A of the fluid injection unit driving voltage asone of the control parameters increases, and at the same time theresting time I as another control parameter is varied by the optimumdriving control parameter calculating device so that the exsection depthis not varied.

This operation makes it possible to reduce the load imposed on thesurgeon or the operator under supervision of the surgeon and the risk ofthe erroneous operation. Furthermore, when fluid is supplied bygravitational force as in the case of this embodiment and the supplyamount of fluid the increase/decrease of which can not be adjusted islimited, the variation of the amount of fluid to be injected isconsequently suppressed. Accordingly, there is an effect that theoperation of the fluid injection device 1 is stable. When the optimumdriving control parameter calculating device is not used, the exsectionhardness adjusting dial 423 may be constructed by a twin switch or atwin variable resistor.

In the above embodiment, it is preferable that the driving wavegenerator 822 is further equipped with an adjusting device (not shown)for setting the optimum gain of the generated driving waveform. Theadjusting device may include a rotary switch, a slide switch, a variablevolume or the like which is provided separately from the exsectionhardness adjusting dial 423. The optimum gain of the driving waveform,that is, the peak voltage of the output driving waveform is stepwiseadjusted by the rotary switch, the slide switch or the like. When thevariable volume is adopted, the peak voltage can be continuouslyadjusted.

Accordingly, only the gain of the driving waveform can be changed byusing the adjusting device before surgery or during surgery, and onlythe gain can be adjusted in accordance with the hardness or exsectiondepth of the surgery site with changing neither the frequency nor thenumber of sequential driving waves, whereby the surgeon can performhis/her desired surgery.

It is preferable that the fluid injection unit 301 is provided with apressure sensor (not shown) as an operation environment detectingelement, the driving waveform generating device 402 is provided with again adjusting circuit (not shown) and the optimum gain of the drivingwaveform is set on the basis of the detection signal from the pressuresensor.

With the above construction, the pressure of the fluid supplied from thefluid infusion bag 411 to the fluid injection unit 301 is detected bythe pressure sensor, the pressure detection value is taken into thedriving waveform generating device 402 and the optimum gain of thedriving waveform is adjusted by the gain adjusting circuit. Accordingly,only the gain can be adjusted in accordance with the hardness and thesurgery depth of the surgery site in connection with the fluid supplypressure without surgeon's adjusting operation of the optimum gain andwithout affecting the frequency and the number of sequential drivingwaves.

Second Embodiment

A fluid injection device according to a second embodiment will bedescribed with reference to FIG. 5 which is a block diagram showing theinternal construction of the driving waveform generating device. Thesecond embodiment is equipped with plural optimum driving controlparameter tables in place of the optimum driving control parametercalculating device of the first embodiment.

When the fluid injection device 1 of this embodiment is used for anoperation or the like, the optimum diameter of the fluid injectionopening portion 334 (see FIG. 3) and the optimum range of the pulsationstate of the fluid stream to be injected vary in accordance with theoperation site. Therefore, it is preferable that these values are setbefore the operation is started and plural control parameters concerninggeneration of pulsation are changed within the optimum range during theoperation.

In FIG. 5, V1 represents a surgery type input, V2 represents a diameterinput value of the fluid injection opening portion 334, and these valuesare set as initial set values. The initial set values may be transmittedfrom a storage unit such as a memory or the like in the fluid injectionunit 301 to the driving waveform generating device 402 by selecting thefluid injection unit 301 having the fluid injection opening portion 334suitable for some operation and connecting it to the driving waveformgenerating device 402. In this case, input of an operator is notrequired, so that the operation can be simplified and the erroneousoperation can be prevented.

Tables 1 and 2 shows examples of different optimum driving controlparameter tables selected on the basis of initial setting values. Theoptimum driving control parameter tables shown in the tables 1 and 2 areselected by a rotary switch or slide switch (not shown) which is onetype of adjusting device. It is preferable that these switches areprotected by a cover or the like so that they are not erroneouslyoperated during surgery.

In the tables 1 and 2, the hardness corresponds to the value representedon the exsection hardness adjusting dial 423, the voltage corresponds tothe amplitude A of the fluid injection unit driving voltage representedin FIG. 4, and the space corresponds to a value obtained when theresting time I is represented by a multiple number of the period T ofthe sine waves constituting the pulsation. In the example of FIG. 4, thenumber n of the sequential sine waves is fixed to 2.

TABLE 1 HARDNESS VOLTAGE SPACE 1 65 4 2 75 5 3 85 6

TABLE 2 HARDNESS VOLTAGE SPACE 1 55 5 2 60 6 3 65 7

The table represented in Table 1 or 2 is selected as the initial setvalue by the rotary switch or the slide switch, and the hardness(exsection hardness V3) is selected by the exsection hardness adjustingdial 423. As compared with Table 1, the amplitude A of the fluidinjection unit driving voltage is smaller with respect to the same valueof the exsection hardness (hardness number) of the exsection hardnessadjusting dial 423 and the space is larger in Table 2. Therefore, Table2 is the optimum driving control parameter table which can be adjustedso as to be suitable for a surgery containing a surgery site containingmany portions having relatively small hardness. The exsection hardnessnumber is indicated from this optimum driving control parameter table,and the driving waveform of the fluid injection unit driving voltage P2is output on the basis of the optimum driving control parameters to thefluid injection unit 301 by the driving waveform generator 822.

The optimum fluid injection states which are respectively suitable fordifferent surgery sites can be easily set by selecting the optimumdriving control parameter table in the manner described above.Furthermore, an erroneous exsection hardness adjusting dial value isprevented from being set during surgery, and thus there is no risk thatfluid having an excessively high exsection hardness is injected, so thatthe operation can be safely and easily performed.

In this embodiment, a pressure sensor as an operation environmentdetecting element (not shown) is provided in the channel of the fluidinjecting unit 301. A supply pressure signal V5 as an output signal ofthe operation environment detecting element for measuring the supplypressure to the fluid injection unit 301 is input to the drivingcontroller 821. When the fluid is supplied to the fluid injection unit301 by the fluid infusion bag 411, the state of the pulsation to beinjected may vary in accordance with the difference in height betweenthe liquid level of the fluid infusion bag 411 and the fluid injectionunit 301. Therefore, the voltage (amplitude A) set in the optimumdriving control parameter table is slightly corrected in accordance withthe supply pressure, thereby further stabilizing the injection of thefluid.

Third Embodiment

Next, the fluid injection device according to a third embodiment will bedescribed with reference to the drawings. The third embodiment ischaracterized in that the optimum driving control parameter tablecorresponds to time-series driving waveform indication values within afixed time range. The construction of the fluid injection device is thesame as the first embodiment, and thus the description thereof isomitted.

TABLE 3 LOW SUPPLY HIGH SUPPLY PRESSURE PRESSURE TIME [μ sec] A1 [V] A2[V] A3 [V] B1 [V] B2 [V] B3 [V] 0 0.0 0.0 0.0 0.0 0.0 0.0 40 6.7 5.4 4.06.0 4.8 3.6 80 25.0 20.0 15.0 22.5 18.0 13.5 120 50.0 40.0 30.0 45.036.0 27.0 160 75.0 60.0 45.0 67.5 54.0 40.5 200 93.3 74.6 56.0 84.0 67.250.4 240 100.0 80.0 60.0 90.0 72.0 54.0 280 93.3 74.6 56.0 84.0 67.250.4 320 75.0 60.0 45.0 67.5 54.0 40.5 360 50.0 40.0 30.0 45.0 36.0 27.0400 25.0 20.0 15.0 22.5 18.0 13.5 440 6.7 5.4 4.0 6.0 4.8 3.6 480 0.00.0 0.0 0.0 0.0 0.0 520 0.0 5.4 4.0 0.0 4.8 3.6 560 0.0 20.0 15.0 0.018.0 13.5 600 0.0 40.0 30.0 0.0 36.0 27.0 640 0.0 60.0 45.0 0.0 54.040.5 680 0.0 74.6 56.0 0.0 67.2 50.4 720 0.0 80.0 60.0 0.0 72.0 54.0 7600.0 74.6 56.0 0.0 67.2 50.4 800 0.0 60.0 45.0 0.0 54.0 40.5 840 0.0 40.030.0 0.0 36.0 27.0 880 0.0 20.0 15.0 0.0 18.0 13.5 920 0.0 5.4 4.0 0.04.8 3.6 960 0.0 1.2 0.9 0.0 1.1 0.8 1000 0.0 0.0 0.0 0.0 0.0 0.0 10400.0 0.0 4.0 0.0 0.0 3.6 1080 0.0 0.0 15.0 0.0 0.0 13.5 1120 0.0 0.0 30.00.0 0.0 27.0 1160 0.0 0.0 45.0 0.0 0.0 40.5 1200 0.0 0.0 56.0 0.0 0.050.4 1240 0.0 0.0 60.0 0.0 0.0 54.0 1280 0.0 0.0 56.0 0.0 0.0 50.4 13200.0 0.0 45.0 0.0 0.0 40.5 1360 0.0 0.0 30.0 0.0 0.0 27.0 1400 0.0 0.015.0 0.0 0.0 13.5 1440 0.0 0.0 4.0 0.0 0.0 3.6 1480 0.0 0.0 0.9 0.0 0.00.8 1520 0.0 0.0 0.0 0.0 0.0 0.0 1560 0.0 0.0 0.0 0.0 0.0 0.0 1600 0.00.0 0.0 0.0 0.0 0.0 1640 0.0 0.0 0.0 0.0 0.0 0.0 1680 0.0 0.0 0.0 0.00.0 0.0 1720 0.0 0.0 0.0 0.0 0.0 0.0 1760 0.0 0.0 0.0 0.0 0.0 0.0 18000.0 0.0 0.0 0.0 0.0 0.0 1840 0.0 0.0 0.0 0.0 0.0 0.0 1880 0.0 0.0 0.00.0 0.0 0.0 1920 0.0 0.0 0.0 0.0 0.0 0.0 1960 0.0 0.0 0.0 0.0 0.0 0.02000 0.0 0.0 0.0 0.0 0.0 0.0

Table 3 shows an example of the optimum driving control parameter tableaccording to the third embodiment. Here, the low supply pressure and thehigh supply pressure respectively correspond to the optimum drivingcontrol parameter tables represented in tables 1 and 2 as the initialset values, and are parameters selected in accordance with the conditionof the surgery site. The selection of the low supply pressure and thehigh supply pressure is performed by the rotary switch or the slideswitch (not shown) as one adjusting device. These switches are protectedby a cover or the like so that they are not erroneously operated duringthe operation. A1-A3 and B1-B3 represent lapse-time-based voltage values(V) of a driving waveform which are selected by the adjusting device(for example, the exsection hardness adjusting dial 423) in accordancewith the exsection hardness of the operation site. The ordinate axisrepresents the lapse time. That is, the optimum driving controlparameter table of Table 3 represents time-series driving waveformindication values within a fixed time range.

FIGS. 6 and 7 show examples of the driving waveform formed on the basisof the optimum driving control parameter table represented in Table 3under the low supply voltage and under the high supply voltage,respectively. The abscissa axis represents the lapse time (micro second,μS), and the ordinate axis represents the voltage value (V). Here, thedriving waveform shown in FIG. 6 will be described by using A1 as arepresentative. The driving waveform of A1 has a pulsating portionhaving such a waveform that the voltage thereof gradually increases fromthe start time, reaches a peak voltage of 100V when 240 μs elapses,gradually decreases from the peak voltage and then reaches 0V at thelapse time of 480 μs. 0V is continued in the range from 480 μs to 2000μs, and this area corresponds to the resting portion (resting period) I.After 2000 μs elapses, the voltage increases again. This cycle isrepeated during the time period when the operation is carried out.

Likewise, A2 represents a driving waveform having a pulsating portion oftwo sequential driving waveforms each of which has a peak voltage of80V, and a resting time (0V) subsequent to the two sequential drivingwaveforms. A3 represents a driving waveform having a pulsating portionof three sequential driving waveforms each of which has a peak voltageof 60V, and a resting time subsequent to the three sequential drivingwaves.

In FIG. 7, the driving waveform represented in Table 3 under high supplyvoltage will be described by using B1 as a representative. The drivingwaveform of B1 has a pulsating portion having a waveform in which thevoltage gradually increases from the start time, reaches a peak voltageof 90V at the lapse time of 240 μs, gradually decreases from the peakvoltage and then reaches 0V at the lapse time of 480 μs. 0V is continuedin the range from the lapse time of 480 μs to 2000 μs, and this areacorresponds to the resting portion I (0V). After 2000 μs elapses, thevoltage increases again. This cycle is repeated.

Likewise, B2 represents a driving waveform having a pulsating portion oftwo sequential driving waveforms each of which has a peak voltage of72V, and a resting time (0V) subsequent to the two sequential drivingwaveforms. B3 represents a driving waveform having a pulsating portionof three sequential driving waveforms each of which has a peak voltageof 54V, and a resting time (0V) subsequent to the three sequentialdriving waveforms.

The waveforms of the pulsating portion and the resting time I shown inFIGS. 6 and 7 are examples, and various combinations may be applied tothe waveform of the pulsating portion (represented by the voltage aftera fixed time elapses, the peak voltage and the period T) and the restingtime I in accordance with the hardness and exsection depth of theoperation site.

The formation of the driving waveform in this embodiment is implementedby reading the time-lapse-based voltage value from the optimum drivingcontrol parameter table represented in Table 3 through a reading unitcontained in the driving waveform generating device 402, shaping therespective voltage values into a continuous waveform through a smoothingwave generator (not shown) and outputting the continuous waveformconcerned.

Accordingly, according to this embodiment, the waveform of the pulsatingportion is not limited to the sine wave, and it is determined on thebasis of the driving waveform indication values of the optimum drivingcontrol parameter table, whereby a more proper fluid injection conditioncan be set in accordance with the hardness or depth of the operationsite.

Fourth Embodiment

Next, a fourth embodiment will be described with reference to FIGS. 8 to10. According to the fourth embodiment, by combining a fluid injectionunit having an outlet channel whose inertance is set to be smaller thanthat of an inlet channel, and a pressure generator that can generate anypressure, the range of the pulsation which can be injected can beenlarged to make the fluid injection device adaptable to variousoperation conditions.

The structure of the fluid injection unit according to the fourthembodiment will be first described. FIG. 8 is a longitudinal sectionalview of the fluid injection unit. In FIG. 8, a recess portion forming afluid chamber 113 is formed in the channel forming member 111. An inletchannel 114 is formed in the side wall of the fluid chamber 113, and anoutlet channel 112 is formed in the side wall at the opposite side. Thetip of the outlet channel 112 serves as a fluid injection openingportion.

One surface of the fluid chamber 113 is sealed by a diaphragm 131. Thediaphragm 131 is provided with a piezoelectric element 141 in advance.In the piezoelectric element 141, the diaphragm 131 is set as oneelectrode, and an electrode member (not shown) is formed on the otherconfronting surface thereof and set as an counter pole electrode. Wiresfrom these electrodes are disposed along the connection tube 201 (notshown). A cover member 122 is fixed to the channel forming member 111 soas to keep a sufficient gap so that the operation of the diaphragm 131and the piezoelectric element 141 is not disturbed.

The maximum outer diameter of the fluid injection unit 101 is set to 3mm or less, preferably to 2 mm or less when the fluid injection deviceis applied to an operation on the brain which requires exsection ofminute portions, etc. Furthermore, when it is applied to a catheter orthe like, the maximum outer diameter is set to 2 mm or less, preferablyto 1 mm or less. The length of the fluid injection unit 101 is requiredto be set to 20 mm or less, preferably to 10 mm or less so that it canbe freely bent. Therefore, the diaphragm 131 and the piezoelectricelement 141 are minute, and the area of the diaphragm 131 whichcontributes to the change of the volume of the fluid chamber 113 isroughly equal to 20 mm² or less, generally to 10 mm² or less. Thedisplacement amount thereof is generally equal to 100 μm or less.

Next, the summary of the fluidity of fluid in this fluid injectiondevice will be described with reference to FIG. 8 and FIG. 9 showing theschematic construction of the fluid injection device according to thisembodiment.

A fluid container and a pump serving as a pressure generator connectedto the fluid container are contained in the supply pressure controldevice 401. The pump is connected to the connection tube 201 so as tofeed out fluid to the connection tube 201. The fluid contained in thefluid container is supplied to the inlet channel 114 through theconnection tube 201 under indicated pressure by the pump. Furthermore,the fluid is injected from the fluid injection opening portion throughthe fluid chamber 113 and the outlet channel 112. The fluid injectionwhen the piezoelectric element 141 is not driven becomes a continuousstream, and the velocity of the stream is low.

The fluid injection of the fluid injection unit 101 of this embodimentis carried out on the basis of the difference between the inertance L1at the inlet channel (which is also called as composite inertance L1)and the inertance L2 at the outlet channel (which is also called ascomposite inertance L2).

First, the inertance will be described. The inertance L is representedby L=ρ×h/S when the density of fluid is represented by ρ, the crosssection of the channel is represented by S and the length of the channelis represented by h. When the pressure difference of the channel isrepresented by ΔP and the flow amount of the fluid flowing in thechannel is represented by Q, the dynamic equation in the channel istransformed by using the inertance L, the relation of ΔP=L×dQ/dt isderived. That is, the inertance L represents the degree of incidenceapplying to the time-variation of the flow amount. Accordingly, as theinertance L increases, the time-variation of the flow amount decreases,and as the inertance L decreases, the time-variation of the flow amountincreases.

Furthermore, the composite inertance concerning the parallel connectionof plural channels or the serial connection of plural channels havingdifferent shapes can be calculated by combining respective inertancevalues of individual channels in the same manner as the parallelconnection or serial connection of inductance in an electrical circuit.

The connection tube 201 for connecting the pulsation and supply pressurecontrol device 401 with the inlet channel has flexibility, and thus itmay be deleted from the calculation of the inertance L1 of the inletchannel side. Furthermore, in this embodiment, the channel length andthe cross sectional area of the inlet channel 114 and the channel lengthand the cross sectional area of the outlet channel 112 are set so thatthe inertance L1 of the inlet channel side is larger than the inertanceL2 of the outlet channel side.

The operation of the fluid injection unit 101 will be described. Fluidis constantly supplied to the inlet channel 114 under indicated liquidpressure by the supply pressure control device 401. As a result, whenthe piezoelectric element 141 does not operate, the fluid flows out fromthe fluid injection opening portion by the fluid resistance of the inletchannel 114, the fluid chamber 113 and the outlet channel 112 and theliquid pressure described above. This flow-out speed of the fluid isvery low, and it has no capability of incising or exsecting a livingbody tissue.

Here, when a driving signal is input to the piezoelectric element 141and thus the piezoelectric element 141 rapidly contracts, the diaphragm131 is rapidly bent in a convex shape so that the volume of the fluidchamber 113 is reduced. As a result, the pressure in the fluid chamber113 rapidly increases and reaches several atms. if the inertance L1, L2of the inlet channel side and the outlet channel side are sufficientlylarge.

This pressure is remarkably larger than the pulsation applied to theinlet channel 114 and the pressure based on the supply pressure controldevice 401. Therefore, the flow-in of the fluid from the inlet channelside into the fluid chamber 113 is reduced by the pressure concerned,and the flow-out of the fluid from the outlet channel 112 is increased.However, the inertance L1 of the inlet channel 114 is larger than theinertance L2 of the outlet channel 112, and thus the increase amount ofthe flow-out of the fluid from the outlet channel 112 is larger than thedecrease amount of the flow-in of the fluid from the inlet channel sideinto the fluid chamber 113. As a result, injection 901 of pulsated fluidfrom the fluid injection opening portion through the outlet channel 112occurs.

Furthermore, the inside of the fluid chamber 113 is set to alow-pressure or vacuum state by the mutual action between the reductionof the flow-in amount of the fluid from the inlet channel 114 and theincrease of the flow-out amount of the fluid from the outlet channel 112just after the pressure increases. As a result, the flow velocity of thefluid of the inlet channel 114 is restored to the same velocity beforethe operation of the piezoelectric element 141 by both the pressure ofthe pulsation and supply pressure control device 401 and thelow-pressure or vacuum state in the fluid chamber 113 after a fixed timeelapses.

If the piezoelectric element 141 contracts after the fluidity of thefluid in the inlet channel 114 is restored, high-speed pulsated fluidcould be continuously injected from the fluid injection opening portion.The continuous state of this pulsated fluid injection is a fluid stream,and this fluid stream can be injected while leaving space(intermittently).

Accordingly, according to the fourth embodiment, the fluid is suppliedto the inlet channel 114 under indicated pressure by the supply pressurecontrol device 401, and the fluid is stably supplied to the fluidinjection unit 101, so that a pump-priming operation, etc. are notrequired in the initializing operation and a desired amount of fluid canbe injected.

Next, the control of the piezoelectric element and the pressuregenerator will be described with reference to FIGS. 8 and 9 and FIG. 10which is a block diagram showing the internal construction of the supplypressure control device 401.

An operation type input V1 and a fluid injection opening portiondiameter input value V2 are input to the driving controller 821. Thistwo kinds of signals may be indicated by a surgeon or an operator in thesupply pressure control device 401, or it may be transmitted to thepulsation and supply pressure control device 401 from a storage unitsuch as a memory or the like which is provided in the fluid injectionunit 101. With this construction, it is unnecessary for the operator toinput, so that the operation can be simplified and the erroneousoperation can be prevented.

The exsection hardness adjusting dial 421 and the exsection depthadjusting dial 422 which are provided to the pulsation and supplypressure control device 401 are adjusted by the surgeon or the operationunder the supervision of the surgeon so as to be adaptable to anoperation (surgery) condition which varies every second. The exsectionhardness indication value V3 and the exsection depth indication value V4which are indicated by the respective adjustment dials are input to thedriving controller 821 in the supply pressure control device 401.

The optimum driving control parameter table is provided in the drivingcontroller 821, and the fluid injection unit driving voltage P2 and thepressure indication value P1 are output as an optimum control parametergroup associated with the injection of the pulsation of the fluid fromthe respective signals described above.

Table 4 shows an example of the optimum driving control parameter table.As in the case of the description on FIG. 4 of the first embodiment, inTable 4, the hardness represents the value of the exsection hardnessadjusting dial 421, the depth represents the value of the exsectiondepth adjusting dial 422, the voltage represents the amplitude A of thefluid injection unit driving voltage, and the space is an multiplenumber of the period T of sine waves constituting the pulsation andrepresents the resting time I (see FIG. 4) between the pulsations.

As in the case of the second embodiment, the number n of sequential sinewaves is fixed to 2. The supply pressure is a pressure indication valuetransmitted to the pressure generator, and its unit is atm. The numberis provided for convenience of description.

The optimum driving control parameter table may be placed not in thedriving controller 821, but in the fluid injection unit 101 by providinga storage unit at the fluid injection unit 101 side. In this case, theoptimum driving control parameter table adapted to the operation type,the opening portion diameter, etc. is provided at the fluid injectionunit 101 side, and the construction is very simple.

TABLE 4 SUPPLY NUMBER HARDNESS DEPTH VOLTAGE SPACE PRESSURE 1 1 1 70 50.1 2 1 2 65 4 0.15 3 1 3 60 3 0.2 4 2 1 80 6 0.15 5 2 2 75 5 0.2 6 2 370 4 0.25 7 3 1 90 7 0.2 8 3 2 85 6 0.25 9 3 3 80 5 0.3

In Table 4, it is assumed that an operation (surgery) is carried outunder the condition of the number 5. The values of the exsectionhardness adjusting dial 421 and the exsection depth adjusting dial 422are equal to 2. Here, when it is required to exsect a tissue having ahigher hardness, the surgeon or the operator under the supervision ofthe surgeon changes the value of the exsection hardness adjusting dial421 from 2 to 3. The condition at this time is set to the number 8. Inthis case, according to the optimum driving control parameter table, theamplitude A of the fluid injection unit driving voltage is changed from75V to 85V. At this time, the space which is the multiple number of theperiod T of the sine waves constituting the pulsations and representsthe resting time I between the pulsations is changed from 5 to 6 so thatthe exsection depth is not increased due to the increase of theamplitude of the pulsations, thereby suppressing increase of the flowamount. Accordingly, the variation of the flow amount itself issuppressed.

Likewise, in the case where the surgeon is carried out under thecondition of the number 5, when the exsection depth is required to beincreased in order to shorten the surgery time or the like, theexsection depth adjusting dial 422 may be changed from 2 to 3. Thecondition at this time is set to the number 6. In this case, accordingto the optimum driving control parameter table, the space is changedfrom 5 to 4, thereby increasing the flow amount. At the same time, theamplitude A of the fluid injection unit driving voltage is changed from75V to 70V so that the hardness indication value of a tissue which canbe exsected is not varied due to the increase of the flow amount.Furthermore, in order to meet the flow amount variation, the supplypressure is increased from 0.2 atm. to 0.25 atm.

As described above, according to the optimum driving control parametertable, plural control parameters are simultaneously changed so as toobtain the fluid injection which the surgeon intends, and thus a desiredcharacteristic can be obtained by a simple operation. Accordingly, theoperation (surgery) time can be shortened, and the erroneous operationcan be prevented, thereby enhancing safety.

The pressure supplied from the supply pressure control device 401 isroughly set to 1 atm. (0.1 MPa) or less, preferably to 0.3 atm. (0.03MPa) or less. When this fluid injection device is applied to a catheteror the like, the fluid injection unit 101 is required to be insertedalong the inside of a blood vessel. Accordingly, it is preferable thatthe connection tube 201 is as flexible as possible. Therefore, it ispreferable that the connection tube 201 is a flexible and thin tube andthe pressure thereof is set to be low to the extent that fluid can befed into the fluid injection unit 101. Therefore, the resistance valuesof the channels of the inlet channel 114, the fluid chamber 113 and theoutlet channel 112 are required to be as small as possible.

Furthermore, the volume variation of the fluid chamber 113 is minute asdescribed above, and in order to effectively use the minute volumevariation for the fluid injection, it is necessary that the increaseamount of the flow-out of the fluid from the outlet channel 112 is setto be larger than the reduction amount of the flow-in of the fluid fromthe inlet channel 114 side into the fluid chamber 113. Therefore, theinertance L1 of the inlet channel 114 is set to be larger than theinertance L2 of the outlet channel 112, and the ratio thereof is set tofive times or more, preferably to ten times or more.

By setting the volume of the inlet channel 114 to a smaller value thanthe volume of the fluid chamber 113, the minute volume variation of thefluid chamber 113 can be suppressed from being lost by the compressioncaused by pressure increase of the fluid in the inlet channel 114 or theenlargement of the volume caused by deformation of surrounding membersof the inlet channel 114, etc.

Furthermore, the length of the outlet channel 112, that is, the channellength from the fluid injection opening portion to the fluid chamber 113is set to the maximum outer diameter of the fluid injection unit 101 orless. This is because the volume variation amount of the fluid chamber113 varies in accordance with the maximum outer diameter of the fluidinjection unit 101 as described above and thus the outlet channel 112which has a shorter length and a smaller loss is required for the fluidinjection unit 101 having a smaller maximum outer diameter.

Specifically, the length of the outlet channel 112 is roughly set to 1mm or less, preferably to 0.5 mm or less. Accordingly, the distancebetween the fluid injection opening portion and the fluid chamber 113 isshorter, and the pulsation occurring in the fluid chamber 113 istransmitted to the fluid injection opening portion without beingattenuated, so that the fluid can be efficiently injected by strongpulsations. Furthermore, by setting the length of the outlet channel 112to a shorter value, the inertance L2 of the outlet channel 112 describedabove can be reduced, so that fluid can be more efficiently injected.

Furthermore, the cross-sectional area of the fluid injection openingportion may be set to be smaller than the cross-sectional area of theoutlet channel 112. In this case, the injection speed of fluid from thefluid injection opening portion can be enhanced without increasing theflow channel resistance and inertance L2 of the outlet channel 112.Furthermore, the injection fluid is more minute, and thus preciseinjection can be performed in the operation on the brain or the like.

Still furthermore, the piezoelectric element 141 and the diaphragm 131are adopted as the volume changing unit, so that the structure can besimplified and thus the miniaturization of the structure can beimplemented. In addition, the maximum frequency of the volume variationof the fluid chamber 113 can be set to a high frequency ranging from 1KHz to 10 KHz or more, and thus this is optimum to injection ofhigh-speed pulsation streams.

Because the high frequency is possible, in the case where the pulsationstate of the fluid stream is varied, even under a pulsation state basedon repetitive fluid streams having a large period in which sine waves of3000 Hz are used as basic waves, the number n of the fluid streams(groups) is equal to 10 and the space is set to 20, the period is equalto 1/100 second, and thus the surgeon can carry out an operation(surgery) without intending any pulsation as in the case of thecontinuous stream.

The entire disclosure of Japanese Patent Application No. 2007-208961,filed Aug. 10, 2007, is expressly incorporated by reference herein.

What is claimed is:
 1. A method of injecting fluid to incise livingtissue by a fluid injection device comprising: a fluid injection unithaving a nozzle configured to inject fluid, a fluid chambercommunicating with the nozzle via an injection tube, and an actuatorconfigured to reduce capacity of the fluid chamber, and a fluid supplyunit configured to supply fluid to the fluid chamber via an inlet tube,the method comprising: a first step of injecting fluid from the nozzlein a continuous manner by the fluid supply unit, wherein the first stepdoes not include driving the actuator; and a second step of injectingfluid from the nozzle in a pulsed manner after the first step by drivingthe actuator in addition to the fluid supply unit, wherein an injectionspeed of fluid in a continuous manner is slower than an injection speedof fluid in a pulsed manner.
 2. The method of injecting fluid to inciseliving tissue according to claim 1, wherein the fluid injection devicefurther comprises a diaphragm sealing the fluid chamber to define acapacity of the fluid chamber, and the second step includes reducingcapacity of the fluid chamber by deforming the diaphragm.
 3. The methodof injecting fluid to incise living tissue according to claim 2, whereina displacement amount of the diaphragm is equal to 100 μm or less. 4.The method of injecting fluid to incise living tissue according to claim1, wherein inertance of the inlet tube is larger than inertance of theinjection tube, and the second step includes: reducing capacity of thefluid chamber to form a higher pressure inside the fluid chamber thanthe pressure applied toward the inlet tube; injecting fluid from thefluid chamber to form a lower pressure inside the fluid chamber than thepressure of the fluid chamber before the fourth step; and restoring flowvelocity of the fluid into the inlet tube.
 5. The method of injectingfluid to incise living tissue according to claim 1, wherein a pressureof fluid supplied from the fluid supply unit when injecting fluid in thepulsed manner and a pressure of the fluid supplied from the fluid supplyunit when injecting fluid in the continuous manner are constant.
 6. Themethod of injecting fluid to incise living tissue according to claim 1,wherein the first step and the second step is repeated alternately tocontinuously form a high-speed pulsated fluid injection.
 7. The methodof injecting fluid to incise living tissue according to claim 1, whereinthe actuator comprises a piezoelectric element.